A Christchurch heritage landmark has been lost, taking with it the irreplaceable memories of almost 50 New Zealand families.

The category-one heritage-listed Fisher's building on the corner of Hereford and High streets, which was built in 1880, was razed last week after it was badly damaged in the February 22 earthquake.

Hanafins Camera and Video owner Lawry Hanafin, whose family links with the building date back to 1920, watched it come down.

Inside were 50 unfinished jobs for the business's Shoebox Scanning service, which takes old slides and negatives and converts them to digital prints.

"There were just boxes of customers' slides that will be generations and generations of their family's history, and that's what I was really trying to get in and save," he said.

"But I got as far as the door to this room and I was with an engineer, and he just said, 'We can't go any further. It's not safe', and at that point another beam came crashing down."

Hanafin was able to retrieve four boxes of slides close to the room's doorway before getting out, just before the demolition. He was yet to figure out who they belonged to. He did not find any other boxes in the jumble of bricks and masonry.

Customers had been surprisingly understanding and sympathetic, he said.

Hanafin's grandfather, James George, set up a pharmacy in the triangular building about 1920 and Lawry Hanafin's shop occupied the building for the past 30 years.

The Venetian Gothic building was designed by one of the country's foremost 19th century architects, William Armson, for clergyman Thomas Richard Fisher, who ran a tea and grocery shop called the Alliance Tea Company.

Armson once had 12 buildings on Hereford St and the three-storeyed Fisher's building, with its lead-lined suspended spiral staircase, was the sole survivor.

Historic Places Trust's southern general manager Malcolm Duff said the Fisher's building was badly damaged during the February quake despite being cared for and strengthened by its owners.

"When heritage buildings such as this go it's not just the building we are losing, it's the social involvement Cantabrians have had with a particular place over many years and we hope that any replacement building will provide a connection with that past for future generations."

Lawry Hanafin said watching the building come down was sad, but also gave him a sense of closure.

Eighteen people were in the building on February 22 and none were injured. Luckily, Hanafin's wife, Jacquie, was out posting some printed photos to their daughter, Annie, in London, when bricks fell into her office.

Inside the toppled building were computers holding all the business's records.

The Hanafins' St Albans home's billiards room has been converted into a makeshift office and storage room.

Because the central-city shop relied on tourism and inner-city workers, Hanafin said he did not see an urgency to reopen there.